A Predator assigned to the 11th Reconnaissance Squadron at Creech Air Force Base, Nev., crashed in May. (Air Force)

Propeller problems and crew mistakes downed an MQ-1B Predator in May near Creech Air Force Base, Nev.

The Predator, assigned to the 11th Reconnaissance Squadron, was flying an eight-hour training mission May 13 that involved four separate ground crews. During the flight, a cable that provides electricity to the system’s motor produced an “inconsistent electrical current,” which caused a drop in thrust, from which the aircraft could not recover, according to an Air Force investigation released Wednesday.

The Air Force’s Accident Investigation Board president found that while aircrews checked the propeller pitch angle hourly, they misinterpreted instrument readings that led them to incorrectly assume that the propeller pitch was acting properly, according to an Air Combat Command release on the investigation. The crew focused on the fact that the propeller pitch angle was within a normal range, rather than recognizing that the number stayed stagnant, according to the Air Force.

The aircraft and one M-36 training missile were destroyed on impact, with a total loss estimated at $4.5 million. There were no injuries or damage to private property.